Liquid-crystal display element

Abstract

An object of the present invention is to provide a liquid-crystal display element using a liquid-crystal composition having negative dielectric anisotropy, capable of realising excellent display characteristics by being used in an FFS mode liquid-crystal display element, without deteriorating various characteristics as a liquid-crystal display element such as dielectric anisotropy, viscosity, a nematic phase upper limit temperature, nematic phase stability at low temperatures, and γ1, and burn-in characteristics of a display element. A liquid-crystal display element containing at least one compound selected from the group consisting of compounds by the following General Formula (I) is provided: wherein each of R 1 and R 2 independently represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an alkenyloxy group having 2 to 8 carbon atoms, A represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, k represents 1 or 2, and in a case where k is 2, two A's may be the same as or different from each other.

The invention claimed is: 
     
       1. A FFS mode liquid-crystal display device, comprising:
 a first substrate and a second substrate disposed to face each other; 
 a liquid-crystal layer containing a liquid-crystal composition with which a gap between the first substrate and the second substrate is filled; 
 an electrode layer including a common electrode including a transparent conductive material, a plurality of gate bus lines and data bus lines disposed in a matrix shape, a thin film transistor provided at the intersection at which the gate bus lines and the data bus lines intersect each other, and a pixel electrode including a transparent conductive material and forming a fringe electric field between the common electrode and the pixel electrode by being driven by the thin film transistor, for each pixel on the first substrate; and 
 photo-alignment film layers inducing homogeneous alignment which are formed between the liquid-crystal layer and the first substrate and between the liquid-crystal layer and the second substrate, respectively, 
 wherein a distance R between the pixel electrode and the common electrode is smaller than a distance G between the first substrate and the second substrate, and 
 the liquid-crystal composition has a negative dielectric anisotropy, a nematic phase-isotropic liquid transition temperature of equal to or higher than 60° C., and an absolute value of dielectric anisotropy of equal to or greater than 2, and contains at least two compounds represented by the following General Formula (I): 
 
       
         
           
           
               
               
           
         
         wherein each of R 1  and R 2  independently represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an alkenyloxy group having 2 to 8 carbon atoms, A represents a trans-1,4-cyclohexylene group, k represents 1, and 
         at least one compound represented by General Formula (II) 
       
       
         
           
           
               
               
           
         
         wherein R 3  represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an alkenyloxy group having 2 to 8 carbon atoms, R 4  represents an an alkoxy group having 1 to 8 carbon atoms, B represents a 1,4-phenylene group, m represents 1. 
       
     
     
       2. The FFS mode liquid-crystal display device according to  claim 1 ,
 wherein the liquid-crystal composition contains at least one represented by the following General Formula (IV): 
 
       
         
           
           
               
               
           
         
         wherein each of R 7  and R 8  independently represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an alkenyloxy group having 2 to 8 carbon atoms, one or more hydrogen atoms in the alkyl group, the alkenyl group, the alkoxy group, or the alkenyloxy group may be substituted with a fluorine atom, any methylene group in the alkyl group, the alkenyl group, the alkoxy group, or the alkenyloxy group may be substituted with an oxygen atom as long as the oxygen atom is not continuously bonded to another oxygen atom or may be substituted with a carbonyl group as long as the carbonyl group is not continuously bonded to another carbonyl group, each of A 1  and A 1  independently represents a 1,4-cyclohexylene group, a 1,4-phenylene group, or a tetrahydropyran-2,5-diyl group, in a case where A 1  or/and A 1  represent a 1,4-phenylene group, one or more hydrogen atoms in the 1,4-phenylene group may be substituted with a fluorine atom, each of Z 1  and Z 2  independently represents a single bond, —OCH 2 —, —OCF 2 —, —CH 2 O—, or CF 2 O—, each of n 1  and n 2  independently represents 0, 1, 2, or 3, n 1  +n 2  is 1 to 3, and in a case where a plurality of A 1 's, A 2 's, Z 1 's, and/or Z 2 's are present, these may be the same as or different from each other, with the proviso that a compound in which n 1  is 1 or 2, n 2  is 0, at least one of A 1 's is a 1,4-cyclohexylene group, and all Z 1 's are single bonds is excluded. 
       
     
     
       3. The FFS mode liquid-crystal display device according to  claim 1 , comprising:
 at least one compound represented by the following General Formula (III) as the compound represented by General Formula (I): 
 
       
         
           
           
               
               
           
         
         wherein R 5  represents a hydrogen atom or a methyl group, and R 6  represents an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. 
       
     
     
       4. The FFS mode liquid-crystal display device according to  claim 2 , comprising: at least one compound selected from the group consisting of compounds represented by the following General Formula (IVa1) or the following General Formula (IVa2) as the compound represented by General Formula (IV): 
       
         
           
           
               
               
           
         
         wherein each of R 7a1 , R 7a2 , R 8a1 , and R 8a2  independently represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an alkenyloxy group having 2 to 8 carbon atoms, one or more hydrogen atoms in the alkyl group, the alkenyl group, the alkoxy group, or the alkenyloxy group may be substituted with a fluorine atom, any methylene group in the alkyl group, the alkenyl group, the alkoxy group, or the alkenyloxy group may be substituted with an oxygen atom as long as the oxygen atom is not continuously bonded to another oxygen atom or may be substituted with a carbonyl group as long as the carbonyl group is not continuously bonded to another carbonyl group, n a2  represents 0 or 1, A 1a2  represents a 1,4-cyclohexylene group, a 1,4-phenylene group, or a tetrahydropyran-2,5-diyl group, and one or more hydrogen atoms in 1,4-phenylene group present in General Formulas (IVa1) and (IVa2) may be substituted with a fluorine atom. 
       
     
     
       5. The FFS mode liquid-crystal display device according to  claim 1 , wherein the pixel electrode has a comb shape or a slit. 
     
     
       6. The FFS mode liquid-crystal display device according to  claim 1 , wherein the distance (R) between the electrodes is 0, and the common electrode is formed on almost the entire surface of the first substrate and disposed at a position closer to the first substrate than the pixel electrode. 
     
     
       7. The FFS mode liquid-crystal display device according to  claim 1 , wherein the photo-alignment film is at least one selected from the group consisting of a photoresponsive decomposition type polymer, a photoresponsive dimerization type polymer, and a photoresponsive isomerization type polymer. 
     
     
       8. The FFS mode liquid-crystal display device according to  claim 1 , further comprising at least one compound represented by the following General Formula (I): 
       
         
           
           
               
               
           
         
         wherein each of R 1  and R 2  independently represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an alkenyloxy group having 2 to 8 carbon atoms, A represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, k represents 1 or 2, and in a case where k is 2, two A's may be the same as or different from each other, and 
         excluding a compound wherein when k is 1, and A is a trans-1,4-cyclohexylene group. 
       
     
     
       9. The FFS mode liquid-crystal display device according to  claim 8 , further comprising at least one compound represented by General Formula (II) 
       
         
           
           
               
               
           
         
         wherein R 3  represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an alkenyloxy group having 2 to 8 carbon atoms, R 4  represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 4 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an alkenyloxy group having 3 to 8 carbon atoms, B represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, m represents 0, 1, or 2, and in a case where m is 2, two B's may be the same as or different from each other, and 
         excluding a compound wherein when m is 0, B is a 1,4-phenylene group and R 4  represents an alkoxy group having 1 to 8 carbon atoms. 
       
     
     
       10. The FFS mode liquid-crystal display device according to  claim 9  wherein the total content of the compounds represented by General Formula (I) and (II) in the liquid crystal composition is 55% by mass to 95%. 
     
     
       11. The FFS mode liquid-crystal display device according to  claim 9 , wherein the liquid-crystal composition contains at least one represented by the following General Formula (IV): 
       
         
           
           
               
               
           
         
         wherein each of R 7  and R 8  independently represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an alkenyloxy group having 2 to 8 carbon atoms, one or more hydrogen atoms in the alkyl group, the alkenyl group, the alkoxy group, or the alkenyloxy group may be substituted with a fluorine atom, any methylene group in the alkyl group, the alkenyl group, the alkoxy group, or the alkenyloxy group may be substituted with an oxygen atom as long as the oxygen atom is not continuously bonded to another oxygen atom or may be substituted with a carbonyl group as long as the carbonyl group is not continuously bonded to another carbonyl group, each of A 1  and A 1  independently represents a 1,4-cyclohexylene group, a 1,4-phenylene group, or a tetrahydropyran-2,5-diyl group, in a case where A 1  or/and A 1  represent a 1,4-phenylene group, one or more hydrogen atoms in the 1,4-phenylene group may be substituted with a fluorine atom, each of Z 1  and Z 2  independently represents a single bond, —OCH 2 —, —OCF 2 —, —CH 2 O—, or CF 2 O—, each of n 1  and n 2  independently represents 0, 1, 2, or 3, n 1 +n 2  is 1 to 3, and in a case where a plurality of A 1 's, A 2 's, Z 1 's, and/or Z 2 's are present, these may be the same as or different from each other, with the proviso that a compound in which n 1 is 1 or 2, n 2  is 0, at least one of A 1 's is a 1,4-cyclohexylene group, and all Z 1 's are single bonds is excluded. 
       
     
     
       12. The FFS mode liquid-crystal display device according to  claim 11 , wherein the total content of the compounds represented by General Formula (I), (II) and (IV) in the liquid crystal composition is 97% by mass to 100%.